Radio receiving system



Patented Apr. 21, 1925.

UNITED STATES 1,534,720 PATENT orncs.

EDWARD W. KELLOGG AND CHESTER W. RICE, 0F SOHENECTADY, NEW YORK, .AS-

SIGNO RS TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

RADIO RECEIVING SYSTEM.

Application filed May 18,

United States, residing at Schenectady, in

the county of. Schenectady, State of New- York, have invented certain new and useful.

Improvements in Radio Receivin Systems,

of which the following is a speci cation.

Our present invention relates to radio re. celvmg systems, and more particularly to recelvmg systems by means of whlch signaling Waves from a desired direction may be received without interference from disturbing waves coming from other directions.

One of the objects of our invention is to provide in conjunction with the unidirectional horizontal receiving antenna, a simple and efficient means whereby the receiving station may be located at any desired-point along the length of the antenna, which may be at some distance from the point in the antenna at which the desired signaling currents are strongest.

In our prior application, Serial No. 372,-

938, filed April 10, 1920, we have describeda receiving antenna which will have marked unidirectional properties. In this case a long horizontal antenna is employed which extends preferably in the general direction of transmission of the signals to be received, and which preferably has a length of at least the order of magnitude of a half wave length of the signal to be received. In case such an antenna is properly constructed signals coming from a desired station will be found to be strongest at the end of the antenna which is farthest from the transmitting station while signals coming from the opposite direction will be very weak at that en In our prior application above referred to we have indicated methods whereby the desired signaling currents may be conveyed by a transmission line'from a point in the antenna where they are strongest, to a receiving station located at some distance from the antenna. A more specific object of our present invention is to provide means whereby the receiving station may be located at a point along the length of the antenna dis tant from the point at which the desired signals are strongest, and whereby the desired signals may be transmitted to the re ceiving apparatus over a transmission line extending parallel with the antenna Without 1921. Serial no. 470,712.

interfering with the desired operation of the receiving system. Another object is to pro- .vide means for protecting the antenna from waves built up in near by wires such as telephone or power lines.

The novel features which we believe to be characteristic of our invention are set forth [with particularity in the appended claims. The invention itself, however, both as to its organization and method of'operation, together with further objects and advantages thereof, .will best be understood by reference to the following description taken in connection with the accompanying drawing in which Figs. 1, 2 and 3, respectively show diagrammatically three different arrange- -ments whereby our invention may be carried into effect.

As indicated in Figs. 1 and 2, we provide a long horizontal antenna made up of two parallel conductors 1 and 2 the opposite ends of which are grounded at 3 and 4. This antenna is preferably so constructed and its constants so adjusted that the current wave thereinwill travel along its length at the same velocity as the signaling wave in space so that the current wave will gradually grow in amplitude as it travels along the conductor. If it is desired to receive a signal which approaches the antenna from the end 3, the amplitude of the current set up in the antenna at 3 by the desired wave will be extremely small while at the end 4 the amplitude of the desired currents will be a maxi-.

mum. It may, however, in some cases, be more convenient to locate the receiving station at some point along the antenna distant from the end 4, as for example, at the end 3 of the antenna. To permit of such location of the receiving station we may provide, as shown in Fig. 1, a transmission line made up of two conductors 5 and 6 extending parallel with the antenna conductors '1- and 2. This transmission line may be supported upon the same poles as the antenna conductors. The transmission line is coupled to the end 40f the antenna by means of a coupling transformer 7. It will be apparent that when arranged in this way the transmission line ceivin tion while currents impressed upon the transmission line by the transformer 7 will flow through the two conductors in opposite directions. In order to prevent the currents produced in the transmission line acting as an antenna from being impressed upon the receiving apparatus 8, the mid points of the secondary of the transformer 7 and the primary of the transformer 9 by means of which the desired signaling currents are impressed upon the receiving apparatus, are grounded through damping resistances 10 and 11, so that any currents which may be received upon the transmission line will flow in opposite directions through the two halves of these transformer windings and will produce equal and opposite effects upon the secondary of transformer 9. As a result the receiver will be unaffected by such currents. The end 3 of the antenna is also preferably grounded through a resistance 12, approximately equal to the surge impedance of the antenna so that no reflection'can occur from this end of the antenna, and therefore no currents will be transferred to the transmission line from waves traveling from the end 4 toward the'end 3 of the antenna.

If the transmission line is constructed so as to have the same velocity of propagation as that of electromagnetic waves in space so that currents produced therein by waves traveling in either direction will build up to a large value, such currents may under some conditions induce in the antenna conductors undesired currents which travel in the antenna conductors in the same direction as in each of the line conductors should preferably be considerably less than half a wave length of the shortest Wave to which the reapparatus is sensitive. Wit t e arrangement thus far described, it will be apfparent that the velocity of propagation o the transmission line may be reduced both for undesired currents and for the desired signaling currents. It may, however, be desirable that the velocity of pgopagation of the signaling currents shall unafiected, and since these currents flow in opposite directions through thetwo conductors of the transmission line, the effect of the loading coils for such currents may be neutralized by coupling the coils of opposite sides of the transmission line together in such a way that the magnetic fields of the two coils oppose for currents flowing in opposite directions in the two conductors, and add for currents flowing in the same direction in the two conductors.

In Fig. 2 We have indicated another method by means of which similar results may be obtained. In this case the transmission line is divided into sections by means of transformers 14 and 15, the length of each section being considerably less than one half of the shortest wave length to which the receiving apparatus is sensitive. These transformers permit of the ready transfer of desired signaling currents, but will not transfer currents flowing in the same direction in the two conductors.

In some cases it may be desirable to employ the transmission line for transferring currents of audio or signaling frequency from one point tofanother. One manner in which the transmission line may be constructed in this case so as to prevent the building up therein of undesired high frequency currents'is indicated in Fig. 3. In this case we have indicated a transmission line conveying signaling currents from terminal apparatus 16 to the receiving apparatus 8. Inductances 17, which will offer a comparatively low impedance to the signaling currents and a high impedance to high frequency currents, may be inserted in the transmission-line, and these induetan'ces ma be shunted by high resistances 18, which wi l absorb the energy of the high frequency currents. Similarly, the high frequency currents may be caused to leak off to the ground connections at 19 through small capacity condensers- 20, and resistances 21.

The condensers 20 will offer a low impedance to the high frequency but a high impedance to the signaling current so that but little of the signaling current will flow through the connection thus established between the two sides of the transmission line.

While we have shown methods of prevent ing disturbances on an antenna resulting from the proximity of wires used as a transmission line in conjunction with the radio receiving system, it is evident that the same methods may be applied to preventing disturbances in an antenna of the type we have described resulting from the proximity of parallel wires used for entirely different purposes, such as telephone, telegraph or power conductors.

While we have shown and described the preferred embodiments of our inventionit is apparent that our invention is by no means limited to the particular arrangements described but that many modifications therein may be made without departing from the scope of our invention as set forth .in the appended claims,

What we claim as new and desire to secure by Letters Patent of the United States, is

1. A receiving system for radio signals comprising a long horizontal receiving antenna, a transmission line running parallel to said antenna for conveying signaling currents from a selected point in said antenna to a distant receiving station, and meansfor preventing undesired inductive efi'ects between the antenna and the transmission line.

comprising a long horizontal receiving an-' tenna, a"transmission line running parallel to said antenna forconveying signaling currents from a selected point in said antenna to a distant receiving station, the constants of said transmission line being so adjusted as to prevent undesired Waves of appreciable magnitude being built up therein.

4. A receiving system for radio signals comprising a long horizontal receiving antenna, a transmission line running parallel to said antenna for conveying signaling currents from a selected point in said antenna to a distant receiving station, and a plurality of loading coils inserted in said transmission line,

5. A receiving system for radio signals comprising a long horizontal receiving antenna, a transmission line made up of two parallel conductors running parallel to said antenna for conveying signaling currents from a selected point in said antenna to a distant receiving station and means for preventing undesired inductive effects between the antenna and the transmission line.

6. A receiving system for radio signals comprising a long horizontal receiving antenna, a transmission line made up of two parallel conductors running parallel to said antenna for conveying signaling currents from a selected point in said antenna to a distant receiving station, the constants of said transmission line being so adjusted that the velocity of propagation of currents transmitted thereby is less than the Velocity of propagation of currents in the antenna.

7. A receiving system for radio signals comprising a long horizontal receiving antenna, a transmission line made up of two parallel conductors running parallel to said antenna for conveying signaling currents from a selectedpoint in said antenna to a distant receiving station, the constants of said transnnssion line being so adjusted as to prevent undesired waves of appreciable magnitude being built up therein.

8. A receiving system for radio signals comprising a long horizontal receiving antenna, a transmision line made upoi two parallel conductors running parallel to said antenna for conveying signaling currents from a selected point in said antenna to a distant receiving station, and a plurality of loading coils inserted in said transmission line.

9. A receiving system for radio signals comprising a long horizontal receiving an tenna, a transmission line made up of two parallel conductors running parallel to said antenna for conveying signaling currents from a selected point in said antenna to a distant receiving station, and a plurality of loading coils inserted in said transmission line, said loading coils being so arranged that the velocity of propagation of currents traveling in the same direction through the two conductors of said trans mission line is less than the velocity of propagation of currents traveling in opposite directions through the two conductors.

10, A receiving system for radio signals comprising a long horizontal receiving antenna, a transmission line made up of two parallel conductors running parallel to said antenna for conveying signaling currents from a selected point in said antenna to a distant receiving station, and a plurality of loading coils inserted in said transmission line, the loading coils in one side of said transmission line being inductively associated with the loading coils in the other side of the transmission line.

11. A receiving system for radio signals comprising a long horizontal receiving antenna, a transmission line running parallel to-said antenna, the constants of said transmission line being so adjusted that the velocity of propagation of currents transmitted thereby is less than the velocity of propagation of currents in the antenna.

12. A receiving system for radio signals comprising a long horizontal receiving antenna, a transmission line running parallel to said antenna, the constants of said trans- 1 mission line being so adjusted as toprevent undesired waves of appreciable magnitude being built up therein.

13. A recelving system for radio signals comprising a, long horizontal receiving antenna, a transmission line running parallel to said antenna, and a plurality of loading coils inserted in said transmission line'for preventing undesired inductive eifects between the antenna and the transmission line.

14:, A receiving system for radio signals comprising a long horizontal receiving a-n-' tenna, a transmission line made up of two parallel conductors running parallel to said antenna the constants of said transmission line being so adjusted that the velocity of propagatlon of currents transmitted thereby is less than the velocity of propagation of currents in the antenna.

, 15. A. receiving system for radio signals comprising a long horizontal receiving antenna, a transmission line made up of two paralllel conductorsrunning parallel to said antenna, the constants of said transmission line being so adjusted as .to prevent undesired waves of appreciable magnitude being built up therein.

16. A receiving system for radio signals comprising along horizontal receiving antenna, a transmission line made up of two parallel conductors running parallel to said antenna, and a plurality of loading coils inserted in said transmission line for preventing undesired inductive eiiects between the antenna and the transmission line.

17 A. receiving system for radio signals comprising a long horizontal receiving antenna, a transmission line made up of two parallel conductors running parallel to said antenna and a plurality of loading coils in serted in said transmission line, said loading coils being so arranged that the velocity of propagation of currents traveling in the same direction through the two conductors of said transmission line is less than the velocity of propagation of currents traveling in opposite directions through the two conductors.

18. A receiving system for radio slgnals comprising a long horizontal receiving antenna a transmission line made up of two paral el conductors running parallel to said antenna, and a plurality of loading coils inserted in said transmission line, the loading coils in one side of said transmission line being inductively associated with the loading coils in the other side of the transmission line.

In witness whereof, we have hereunto set our hands this 17th day of May, 1921.

EDWARD W. KELLOGG. CHESTEB W. RICE. 

